Microporous membranes comprising a hydrophobic polymeric matrix with a hydrophilic, finely divided, particulate filler distributed throughout the matrix are well known. Such materials are available from PPG Industries under the trademark TESLIN®. With TESLIN membranes, the polymeric matrix is a polyolefin such as polyethylene and the filter is a siliceous material such as fumed silica. These membranes have a network of interconnecting pores communicating throughout the microporous membrane. These membranes have interesting properties and have been used in stationery and signage applications as well as being used in filtration applications.